This invention relates generally to devices for separating particulates, such as dirt and dust, from air that is recirculated in a vacuum or pneumatic conveying system.
Air precleaners are devices typically used in the removal of dust, dirt, sand, and other airborne particulates prior to the flow of air through a filter. The efficiency of the precleaner is determined by the percentage of particulates that are removed from the intake air by the precleaner. The more efficient the precleaner, the lesser the amount of particulates that must be removed by the air filter.
Many enclosed air circulation systems require that a very clean environment be maintained internally. For example, enclosures for sensitive manufacturing processes, such as those used in the food, pharmaceutical, and semiconductor industries, may be subject to strict air quality controls. In addition, enclosures housing sensitive instrumentation must maintain a clean air environment in order to ensure adequate performance of the instrumentation. In these enclosures, particulate contamination may originate from inside the enclosure from internal sources.
In addition, systems that induce air flow or circulation using vacuum pumps, blowers, or compressors are subject to increased wear and reduced lifetimes due to the damaging effects of particulate-contaminated air on these components. Such systems stand to benefit from an efficient air precleaner that removes particulate contaminants before they are taken into the machinery of the systems.
The precleaners of the prior art have various configurations that are employed as a means of removing the particulates from the air. Most of these precleaners are adapted to operate in open air systems, such as the air intake system on an internal combustion engine, which draw ambient air into the system. Examples of precleaners or particle separators are shown in U.S. Pat. Nos. 1,641,746; 2,193,479; 2,304,778; 2,417,130; 2,973,830; 3,552,102; 3,670,480; 3,740,932; 3,791,112; 3,973,937; 4,138,761; 4,197,102; 4,547,207; 5,022,903; 5,449,391; 5,505,756; and 6,264,712.
Although such precleaners may be suited for particulate removal in an open system, they are not designed to remove particulates contained within a vacuum system.
The present invention provides a precleaner for mechanically removing particulate contaminants from a vacuum system. In these systems, the precleaner may be inserted between a chamber under vacuum and the air pressure differential source that creates the vacuum in order to protect the air pressure differential source from particulate contaminants. Exemplary systems in which the precleaner may be used include, but are not limited to, closed vacuum systems and pneumatic conveyor systems. In these systems air flow may controlled by such devices as vacuum pumps, blowers, and air compressors.
The air precleaner in accordance with the present invention provides high efficiency removal of particulates from a vacuum system while significantly reducing the air flow restriction or pressure drop, encountered in the conventional air precleaners. The air precleaner of the invention includes a peripheral air intake manifold having at least one air intake port; a mechanical separation unit coupled to the intake manifold, the separation unit having an input port in fluid communication with the at least one intake port of the intake manifold, an output port for expelling precleaned air, and a base having at least one discharge port for discharging particulates from the mechanical separation unit; and a central exhaust pipe disposed in fluid communication with the output port of the mechanical separation unit. The intake manifold and the mechanical separation unit are housed in a container having an entrance port and an exit port. Optionally, an entrance fitting and an exit fitting may be mounted to the entrance and exit ports, respectively. The container includes a removable canister that surrounds a portion of the separation unit and receives and holds particulates discharged therefrom. The entrance port on the container is in fluid communication with the at least one intake port on the intake manifold and the exit port on the container is in fluid communication with the exhaust pipe. The exhaust pipe may be coupled to the fitting assembly, the intake manifold, the particle separator, or the canister, in such a manner that it extends into or through the opening defined by the peripheral intake manifold when the precleaner is operating. This configuration defines an air space that extends from the entrance port through the intake manifold, the mechanical separation unit, and the exhaust pipe to the exit port. Both the entrance and exit fittings are adapted to allow the precleaner to be inserted into or onto a vacuum system from which airborne particulates are to be removed. For example, the precleaner may be coupled to a tube, pipe, or duct.
In a preferred embodiment, the container housing the intake manifold and the mechanical separation unit is a two part container formed from an upper fitting assembly and a lower canister. The fitting assembly includes the entrance and exit ports of the precleaner and their respective fittings, while the canister encloses the mechanical separation unit. The particulate matter that is separated from the air is collected in the canister. The two parts are preferably easily separated such that the canister can be removed and the particulate matter periodically disposed of.
In one embodiment, the base of the mechanical separation unit may include a side wall with a peripheral top edge and a flange extending outwardly from the top edge to the inner surface of the canister to separate the canister into a top compartment and a bottom compartment which are substantially sealed off from each other. The discharge port is in communication with the bottom compartment. This configuration allows the particulates that are discharged through the discharge port in the mechanical separation unit to be collected in the bottom compartment of the canister and prevents the particulates from being drawn back into the separation unit.
As air in the vacuum system is drawn through the precleaner, the moving air passes through the intake manifold. The air then enters the mechanical separation unit where a preferably tangential component of the flow forces the particulate matter within the air against the side wall of the base, and ultimately, toward the discharge port. A rotor may be rotably mounted to the base of the mechanical separation unit. When the rotor is rotating it physically impels the particulates from the air downwardly and outwardly into the side wall of the base toward the discharge port, enhancing particulate separation. The precleaned air is released from the mechanical separation unit through the central exhaust pipe where it is discharged into the vacuum system through the exit port of the precleaner.
In one embodiment of the invention, the precleaner is inserted into or onto an enclosed vacuum system. The enclosure is formed when the precleaner is inserted into or onto a vacuum chamber or loop made from coupled containers, tubes, pipelines, ducts and the like, to form a closed system. The air is drawn from the enclosed systems using an air pressure differential source (i.e. a vacuum source) that creates a lower than ambient pressure within the system. The air may be drawn from the system using pumps, blowers, and compressors. In this configuration the precleaner is coupled to the vacuum chamber or loop such that the input port of the precleaner is in fluid communication with the chamber or loop and the output port of the precleaner is in fluid communication with a suction port on the suction side of the vacuum source. In one embodiment the air in the system may be primarily recycled or recirculated air, as opposed to air that is constantly being brought in from outside of the system. Air recirculation systems in which the precleaner of the present invention may be used are commonly employed in food processing and pharmaceutical and semiconductor manufacturing plants.
In another embodiment of the invention, the precleaner is inserted into a pneumatic conveyor system. In a pneumatic conveyor system, pressure differentials are used to regulate the airflow through the system. In this embodiment the precleaner may be coupled to the inlet of the air pressure source that creates the airflow. Examples of air pressure sources include pumps, compressors, and blowers.